Ancestral Land sold without consent

We had around 10 acre ancestral property near Pune. It belonged to two brothers (our great grandfathers), suppose X and Y. In the 7/12, only the name of X was showed up. And X sold of the land. When we filed a case, X proved in the court that Y was never his brother. Y was born somewhere in the 18th Century hence proving it difficult for us to get any birth records. Y died in a hospital in Pune in 1953, when we contacted the hospital for the same during the case trail for death certificate, they denied saying there is no record existing. Hence the case was not turned in our favor.